Motorcycle Repair: Front Brakes Go Away, ft altitude, suzuki gsxr 600

Question
Understand you expertise is Honda, but this should apply to all models.  Currently racing a Suzuki GSXR-600. Brakes were fine 3 weeks ago.  Bike remained in a trailer for the 3 week period.  Weather was hot, appx. 100 each day.  Now the brakes initially work fine for about 2 laps then go away and the front brake lever comes to the grip.  Bled the system 3 times with high temp fluid.  No change.  Replaced the master cylinder. No change.  There are no leaks or loss of brake fluid anywhere.  After returning to the pit area and waiting a few minutes.  The brakes seem normal again and appear to work as they should.  Any ideas?  Thanks for any help you can give.

Answer
There are a couple things I can think of.  First is boiling.  If the brakes get hot enough to boil the fluid, the brakes will go away.  The second cause could be vacuum in the master cylinder. I had a similar thing happen at 9000 ft altitude.  My clutch quit working.  Since you probably aren't racing at altitude, I'm betting you are boiling the fluid.

Regards,
Rich